Process for the inductive heating of a fireproof molding and a suitable molding therefor

Abstract

A refractory guide member and a method for heating the refractory guide member by use of an inductor, where at least one collateral electromagnetic field located in a region spaced apart from the inductor is generated by the inductor. The mold part is made of an electrically conductive layer with several insulating interrupting slots for the controlled deflection of eddy currents from a main field generated by the inductor into a region spaced apart from the inductor.

We claim: 
     
       1. A method of inductively heating an electrically conductive guide member employed to guide molten metal, said method comprising: employing an inductor to generate a main field in a first region of said electrically conductive guide member, thereby inductively heating said first region and producing eddy currents; and   diverting at least a part of said eddy currents from said first region of said electrically conductive guide member to a second region thereof, that is not acted upon by said main field, by electrically non-conductive interruptions in said electrically conductive guide member including at least one electrically non-conductive interruption positioned between said first region and said second region, thereby inductively heating said second region;   wherein said electrically conductive guide member has an inner surface, an outer surface, and an electrically insulating slot which extends continuously in a longitudinal direction;   wherein said inner surface has an electrically insulating surface formed thereon;   wherein said outer surface of at least said second region has an electrically insulating surface formed thereon; and   wherein said electrically non-conductive interruptions are comprised of at least two electrically insulating transverse slots formed in said electrically conductive guide member which extend around nearly an entire circumference of said electrically conductive guide member, and at least one electrically insulating longitudinal slot connecting said at least two electrically insulating transverse slots.   
     
     
       2. The method of claim 1, wherein: said electrically conductive guide member is a ceramic immersion casting tube introducing molten metal into a mold.   
     
     
       3. The method of claim 1, wherein: said electrically conductive guide member is a ceramic feed channel placing molten metal onto a conveyor device.   
     
     
       4. The method of claim 1, wherein: said electrically conductive guide member has a specific electrical resistance of less than 1000 Ohm mm 2  /m.   
     
     
       5. The method of claim 1, wherein: said electrically conductive guide member has a specific electrical resistance of less than 200 Ohm mm 2  /m.   
     
     
       6. The method of claim 1, wherein: said electrically conductive guide member is composed of a carbon-containing refractory material.   
     
     
       7. The method of claim 1, wherein: said electrically conductive guide member is composed of a carbon-bound graphite containing Al 2  O 3 .   
     
     
       8. The method of claim 1, further comprising: inserting an electrically insulated dividing wall longitudinally within said electrically conductive guide member.   
     
     
       9. The method of claim 1, wherein: said at least one electrically insulating longitudinal slot is located in a third region interposed between said first and said second regions.   
     
     
       10. The method of claim 1, wherein: said electrically insulating layer of said inner surface and said electrically insulating layer of said outer surface are composed of an electrically non-conductive refractory material.   
     
     
       11. The method of claim 1, wherein: said electrically insulating layer of said inner surface and said electrically insulating layer of said outer surface are composed of ZrO 2 .   
     
     
       12. An electrically conductive guide member that is to be inductively heated while being employed to guide molten metal, said electrically conductive guide member comprising: a first region to be inductively heated by the generation therein of a main field by an inductor;   a second region not to be acted upon by said main field; and   electrically non-conductive interruptions located in said electrically conductive guide member including at least one electrically non-conductive interruption positioned between said first region and said second region to divert at least a part of eddy currents produced by said main field from said first region to said second region and thereby to inductively heat said second region;   wherein said electrically conductive guide member has an inner surface, an outer surface, and an electrically insulating slot which extends continuously in a longitudinal direction;   wherein said inner surface has an electrically insulating surface formed thereon; wherein said outer surface of at least said second region has an electrically insulating surface formed thereon; and   wherein said electrically non-conductive interruptions are comprised of at least two electrically insulating transverse slots formed in said electrically conductive guide member which extend across said electrically conductive guide member, and at least one electrically insulating longitudinal slot connecting said at least two electrically insulating transverse slots.   
     
     
       13. The electrically conductive guide member of claim 12, wherein: said electrically conductive guide member is a ceramic immersion casting tube capable of introducing molten metal melt a mold.   
     
     
       14. The electrically conductive guide member of claim 12, wherein: said electrically conductive guide member is a ceramic feed channel capable of placing molten metal onto a conveyor device.   
     
     
       15. The electrically conductive guide member of claim 12, wherein: said electrically conductive guide member has a specific electrical resistance of less than 1000 Ohm mm 2  /m.   
     
     
       16. The electrically conductive guide member of claim 12, wherein: said electrically conductive guide member has a specific electrical resistance of less than 200 Ohm mm 2  /m.   
     
     
       17. The electrically conductive guide member of claim 12, wherein: said electrically conductive guide member is composed of a carbon-containing refractory material.   
     
     
       18. The electrically conductive guide member of claim 12, wherein: said electrically conductive guide member is composed of a carbon-bound graphite containing Al 2  O 3 .   
     
     
       19. The electrically conductive guide member of claim 12, wherein: said at least two electrically insulating transverse slots extend around nearly an entire circumference of said electrically conductive guide member.   
     
     
       20. The electrically conductive guide member of claim 12, wherein: an electrically insulated dividing wall is longitudinally provided within said electrically conductive guide member.   
     
     
       21. The electrically conductive guide member of claim 12, wherein: said at least one electrically insulating longitudinal slot is located in a third region interposed between said first and said second regions.   
     
     
       22. The electrically conductive guide member of claim 12, wherein: said electrically insulating layer of said inner surface and said electrically insulating layer of said outer surface are composed of an electrically non-conductive refractory material.   
     
     
       23. The electrically conductive guide member of claim 12, wherein: said electrically insulating layer of said inner surface and said electrically insulating layer of said outer surface are composed of ZrO 2 .   
     
     
       24. An assembly, comprising: a electrically conductive guide member to be employed to guide molten metal, said electrically conductive guide member including a first region, a second region and electrically non-conductive interruptions including at least one electrically non-conductive interruption positioned between said first region and said second region;   an inductor positioned to generate a main field acting on said first region, thereby to inductively heat said first region and to produce eddy currents, and not acting on said second region; and   wherein said electrically non-conductive interruptions are located to divert at least a part of said eddy currents from said first region to said second region, thereby to inductively heat said second region;   wherein said electrically conductive guide member has an inner surface, an outer surface, and an electrically insulating slot which extends continuously in a longitudinal direction;   wherein said inner surface has an electrically insulating surface formed thereon;   wherein said outer surface of at least said second region has an electrically insulating surface formed thereon; and   wherein said electrically non-conductive interruptions are comprised of at least two electrically insulating transverse slots formed in said electrically conductive guide member which extend across said electrically conductive guide member, and at least one electrically insulating longitudinal slot connecting said at least two electrically insulating transverse slots.   
     
     
       25. The assembly of claim 24, wherein: said electrically conductive guide member is a ceramic immersion casting tube capable of introducing molten metal into a mold.   
     
     
       26. The assembly of claim 24, wherein: said electrically conductive guide member is a ceramic feed channel capable of placing molten metal onto a conveyor device.   
     
     
       27. The assembly of claim 24, wherein: said electrically conductive guide member has a specific electrical resistance of less than 1000 Ohm mm 2  /m.   
     
     
       28. The assembly of claim 24, wherein: said electrically conductive guide member has a specific electrical resistance of less than 200 Ohm mm 2  /m.   
     
     
       29. The assembly of claim 24, wherein: said electrically conductive guide member is composed of a carbon-containing refractory material.   
     
     
       30. The assembly of claim 24, wherein: said electrically conductive guide member is composed of a carbon-bound graphite containing Al 2  O 3 .   
     
     
       31. The assembly of claim 24, wherein: said at least two electrically insulating transverse slots extend around nearly an entire circumference of said electrically conductive guide member.   
     
     
       32. The assembly of claim 24, wherein: an electrically insulated dividing wall is longitudinally provided within said electrically conductive guide member.   
     
     
       33. The assembly of claim 24, wherein: said at least one electrically insulating longitudinal slot is located in a third region interposed between said first and said second regions.   
     
     
       34. The assembly of claim 24, wherein: said electrically insulating layer of said inner surface and said electrically insulating layer of said outer surface are composed of an electrically non-conductive refractory material.   
     
     
       35. The assembly of claim 24, wherein: said electrically insulating layer of said inner surface and said electrically insulating layer of said outer surface are composed of ZrO 2 .